Question

The functional groups that are responsible for the ion-exchange property of cation and anion exchange resins, respectively, are:

• A. $-S{O}_{3}H\text{and}-COOH$
• B. $-S{O}_{3}H\text{and}-N{H}_2$
• C. $N{H}_2\text{and}-S{O}_{3}H$
• D. $-N{H}_2\text{and}-COOH$

Answer 1

The correct option is B $-S{O}_{3}H\text{and}-N{H}_2$

There are two general types of ion exchange resins: those that exchange positive ions are called cation exchange resins, and those that exchange negative ions are called anion exchange resins.
$-S{O}_{3}H\text{and}-COOH$ are cation exchange resin. In cation exchange process $H^{+}$ exchanges for $N{a}^{+},C{a}^{2+},M{g}^{2+}$ and other cations present in water.

While anion exchange resins contain $–NH2$ in form of $–N{H}_3^{+}O{H}^{–}$ where $OH–$ exchanges for anions like $C{l}^{–},HCO{3}^{–},S{O}_4^{2–},etc.$